The disclosure of the following priority application is herein incorporated by reference:
Japanese Patent Application No. 2000-032114 filed Feb. 9, 2000
1. Field of the Invention
The present invention relates to a microscope mainly used in the fields of biology and medicine, which may be, for instance, an epi-fluorescence microscope (or a top-lighting fluorescence microscope) employed to observe a test piece with the fluorescent light originating from the test piece being lit from above with excitation light.
2. Description of the Related Art
There is a method of fluorescence microscopy in the known art in which a specific tissue in a test piece is dyed with a reagent coupled with a fluorescent dye and the specific tissue is observed with the fluorescent light generated by the reagent by irradiating excitation light on the test piece. An illumination optical system in an epi-fluorescence microscope used in the fluorescent microscopy method comprises a light source, an excitation filter, a dichroic mirror and an absorption filter. The excitation filter allows only light (excitation light) having a wavelength effective for generating fluorescent light from the fluorescent dye in the test piece, in the light emitted by the light source, to be transmitted. The dichroic mirror is positioned at a 45xc2x0 angle of inclination relative to the optical axis of the observation optical system constituted of the objective optical system and the eyepiece optical system of the epi-fluorescence microscope, and the excitation light is reflected by the dichroic mirror to be guided to the test piece. The excitation light thus guided to the test piece causes the dye in a specific tissue to generate fluorescent light. The wavelength of this fluorescent light is larger than the wavelength of the excitation light, and the dichroic mirror mentioned above achieves spectral transmission characteristics that allow the fluorescent light to be transmitted. The absorption filter is provided on the optical path of the observation optical system located between the dichroic mirror and the eyepiece optical system to eliminate any superfluous excitation light component reflected by the test piece or the like and traveling toward the eyepiece optical system.
By employing the epi-fluorescence microscope described above, a clear observation image can be obtained since the specific tissue which generates light can be observed in a field of perfect black.
However, the contrast of the observation image may become lowered if part of the excitation light is guided to the eyepiece optical system. For instance, after part of the excitation light that has been transmitted through the dichroic mirror and has advanced linearly is reflected by the wall surface present behind the dichroic mirror, it is reflected at the rear surface of the dichroic mirror and is guided to the eyepiece optical system. Hereafter in this specification, the excitation light, which is not reflected by the dichroic mirror and is transmitted through the dichroic mirror to reach the eyepiece optical system as described above is referred to as xe2x80x9cstray lightxe2x80x9d.
The absorption filter is provided to absorb such stray light to prevent it from entering the eyepiece optical system. However, if the spectral transmission characteristics of the absorption filter are those achieved by an interference filter that are determined in conformance to the film thickness of the interference film instead of those achieved by a so-called dye filter, desired spectral transmission characteristics cannot be realized with regard to light entering diagonally relative to the light entry surface of the absorption filter. Since the excitation light reflected by the wall surface mentioned earlier undergoes irregular reflection at the wall surface, not all the excitation light entering the light entry surface of the absorption filter advances in the direction perpendicular to the entry surface. As a result, some of the excitation light is transmitted through the absorption filter and advances toward the eyepiece optical system as stray light.
The quantity of the fluorescent light originating from the dye material is extremely small, at 10xe2x88x926xcx9c10xe2x88x929 relative to the quantity of the excitation light set at 1. Thus, the effect of the stray light advancing toward the eyepiece optical system as described above on the observation image cannot be disregarded.
An object of the present invention is to provide a microscope capable of minimizing the degree to which the contrast of the observation image is lowered by illuminating light entering the eyepiece optical system.
In order to attain the above object, an epi-fluorescence microscope according to the present invention comprises: a light guiding device that guides illuminating light emitted by a light source by reflecting the illuminating light to implement epi-lighting on a test piece, and guides fluorescent light excited by the illuminating light and generated from the test piece to an observation unit by allowing the fluorescent light to be transmitted; and an inclined member that is provided on an optical path of transmitted light which is a part of the illuminating light and has been transmitted through the light guiding device instead of being reflected by the light guiding device, and has a surface inclined relative to the optical path.
In this epi-fluorescence microscope, it is preferred that the inclined member attenuates the transmitted light and reflects an attenuated transmitted light by the inclined surface along a direction other than a direction toward the light guiding device. In this case, it is preferred that the epi-fluorescence microscope further comprises a light attenuating member that is provided on an optical path of the attenuated transmitted light having been reflected by the inclined member to further attenuate the attenuated transmitted light.
Another epi-fluorescence microscope according to the present invention comprises: a light guiding device that guides illuminating light emitted by a light source by reflecting the illuminating light to implement epi-lighting on a test piece, and guides fluorescent light excited by the illuminating light and generated from the test piece to an observation unit by allowing the fluorescent light to be transmitted; and a frame body that holds the light guiding device on an optical axis of an observation optical system, and an opening is provided at a wall surface of the frame body intersecting an optical path of transmitted light that is a part of the illuminating light and has been transmitted through the light guiding device instead of being reflected at the light guiding device.
In this epi-fluorescence microscope, it is preferred that a light attenuating device that is provided rearward of the opening to prevent the transmitted light from being reflected to advance toward the light guiding device, is further provided. Or, it is preferred that a reflecting device that is provided rearward of the opening to bend the optical path of the transmitted light by reflecting the transmitted light, is further provided.
Another epi-fluorescence microscope according to the present invention comprises: a light guiding device that guides illuminating light emitted by a light source by reflecting the illuminating light to implement epi-lighting on a test piece, and guides fluorescent light excited by the illuminating light and generated from the test piece to an observation unit by allowing the fluorescent light to be transmitted; a frame body that hods the light guiding device on an optical axis of an observation optical system; a first light attenuating device that is provided on an optical path of transmitted light which is a part of the illuminating light and has been transmitted through the light guiding device instead of being reflected by the light guiding device, and attenuates a quantity of the transmitted light; and one or more second light attenuating devices that are provided on an optical path along which light having been attenuated at the first light attenuating device advances, and further attenuates a quantity of an attenuated transmitted light.
Another epi-fluorescence microscope according to the present invention comprises: a plurality of light guiding devices each provided to guide illuminating light emitted by a light source by reflecting the illuminating light to implement epi-lighting on a test piece, and guide fluorescent light excited by the illuminating light and generated from the test piece to an observation unit by allowing the fluorescent light to be transmitted; a holding device that selectively holds one of the plurality of light guiding devices at an optical axis of an observation optical system; and a light attenuating device that prevents transmitted light, which is a part of the illuminating light entering the light guiding device held at the optical axis and has been transmitted through the held light guiding device instead of being reflected by the held light guiding device, from being reflected to be allowed to advance toward the light guiding device.
In this epi-fluorescence microscope, it is preferred that: the holding device is a turret device capable of rotating around a rotational axis extending almost parallel to the optical axis of the observation optical system and having the plurality of light guiding devices mounted radially along an arch around the rotational axis; and the light attenuating device is provided near the rotational axis.
Also, it is preferred that the light attenuating device is commonly utilized regardless of which of the plurality of light guiding devices is held at the optical axis of the observation optical system.
A microscope according to the present invention comprises: a light guiding device that guides illuminating light emitted from a light source to illuminate a test piece and guides light from the test piece toward an observation unit; and a member that is provided at a position outside an observation optical path and having a surface inclined relative to an optical path of the light guiding device. And: the light guiding device guides the illuminating light to an objective lens group which irradiates the test piece and guides a part of the illuminating light to a position other than the objective lens group to result in generation of stray light; and the stray light is eliminated at a preceding stage before the stray light enters the objective lens group by the member having the inclined surface.
Another microscope according to the present invention comprises: a light guiding device that guides illuminating light emitted from a light source to illuminate a test piece and guides light from the test piece toward an observation unit; and a stray light attenuating device that is provided on an optical path of stray light which is a part of the illuminating light that has not been guided by the light guiding device to illuminate the test piece, and has a reflecting surface which inclines at a specific angle of inclination relative to the optical path of the stray light so that the stray light is not guided back to the light guiding device.
In this microscope, it is preferred that the reflecting surface of the stray light attenuating device comprises a member that attenuates the stray light and reflects attenuated stray light along a direction other than a direction toward the light guiding device.